First galaxies were born much earlier than expected (w/ video)

April 12, 2011

The giant cluster of elliptical galaxies in the centre of this image contains so much dark matter mass that its gravity bends light. This means that for very distant galaxies in the background, the cluster’s gravitational field acts as a sort of magnifying glass, bending and concentrating the distant object’s light towards Hubble. These gravitational lenses are one tool astronomers can use to extend Hubble’s vision beyond what it would normally be capable of observing. Using Abell 383, a team of astronomers have identified and studied a galaxy so far away we see it as it was less than a billion years after the Big Bang. Viewing this galaxy through the gravitational lens meant that the scientists were able to discern many intriguing features that would otherwise have remained hidden, including that its stars were unexpectedly old for a galaxy this close in time to the beginning of the Universe. This has profound implications for our understanding of how and when the first galaxies formed, and how the diffuse fog of neutral hydrogen that filled the early Universe was cleared. Credit: NASA, ESA, J. Richard (CRAL) and J.-P. Kneib (LAM). Acknowledgement: Marc Postman (STScI)

(PhysOrg.com) -- Using the amplifying power of a cosmic gravitational lens, astronomers have discovered a distant galaxy whose stars were born unexpectedly early in cosmic history. This result sheds new light on the formation of the first galaxies, as well as on the early evolution of the Universe.

Johan Richard, the lead author of a new study says: "We have discovered a distant galaxy that began forming stars just 200 million years after the Big Bang. This challenges theories of how soon galaxies formed and evolved in the first years of the Universe. It could even help solve the mystery of how the hydrogen fog that filled the early Universe was cleared."

This video shows a phenomenon known as gravitational lensing, which is used by astronomers to study very distant and very faint galaxies. Credit: NASA, ESA

The distant galaxy is visible through a cluster of galaxies called Abell 383, whose powerful gravity bends the rays of light almost like a magnifying glass. The chance alignment of the galaxy, the cluster and the Earth amplifies the light reaching us from this distant galaxy, allowing the astronomers to make detailed observations. Without this gravitational lens, the galaxy would have been too faint to be observed even with today's largest telescopes.

After spotting the galaxy in Hubble and Spitzer images, the team carried out spectroscopic observations with the Keck-II telescope in Hawaii. Spectroscopy is the technique of breaking up light into its component colours. By analysing these spectra, the team was able to make detailed measurements of its redshift and infer information about the properties of its component stars.

The galaxy's redshift is 6.027, which means we see it as it was when the Universe was around 950 million years old. This does not make it the most remote galaxy ever detected  several have been confirmed at redshifts of more than 8, and one has an estimated redshift of around 10 (heic1103), placing it 400 million years earlier. However the newly discovered galaxy has dramatically different features from other distant galaxies that have been observed, which generally shine brightly with only young stars.

"When we looked at the spectra, two things were clear," explains co-author Eiichi Egami. "The redshift placed it very early in cosmic history, as we expected. But the Spitzer infrared detection also indicated that the galaxy was made up of surprisingly old and relatively faint stars. This told us that the galaxy was made up of stars already nearly 750 million years old  pushing back the epoch of its formation to about 200 million years after the Big Bang, much further than we had expected."

Co-author Dan Stark continues: "Thanks to the amplification of the galaxy's light by the gravitational lens, we have some excellent quality data. Our work confirms some earlier observations that had hinted at the presence of old stars in early galaxies. This suggests that the first galaxies have been around for a lot longer than previously thought."

This illustration shows a phenomenon known as gravitational lensing, which is used by astronomers to study very distant and very faint galaxies. Note that the scale has been greatly exaggerated in this diagram. In reality, the distant galaxy is much further away and much smaller. Lensing clusters are clusters of elliptical galaxies whose gravity is so strong that they bend the light from the galaxies behind them. This produces distorted, and often multiple images of the background galaxy. But despite this distortion, gravitational lenses allow for greatly improved observations as the gravity bends the light’s path towards Hubble, amplifying the light and making otherwise invisible objects observable. A team of astronomers has used Abell 383, one such gravitational lens, to observe a distant galaxy whose light is resolved into two images by the cluster. The gravitational lensing effect means that astronomers have been able to determine fascinating insights about the galaxy that would not normally be visible even with Hubble or large ground-based telescopes. Among their discoveries is that the distant galaxy’s stars are very old, meaning that galaxies probably formed earlier in cosmic history than we first thought. Credit: NASA, ESA

The discovery has implications beyond the question of when galaxies first formed, and may help explain how the Universe became transparent to ultraviolet light in the first billion years after the Big Bang. In the early years of the cosmos, a diffuse fog of neutral hydrogen gas blocked ultraviolet light in the Universe. Some source of radiation must therefore have progressively ionised the diffuse gas, clearing the fog to make it transparent to ultraviolet rays as it is today  a process known as reionisation.

Astronomers believe that the radiation that powered this reionisation must have come from galaxies. But so far, nowhere near enough of them have been found to provide the necessary radiation. This discovery may help solve this enigma.

"It seems probable that there are in fact far more galaxies out there in the early Universe than we previously estimated  it's just that many galaxies are older and fainter, like the one we have just discovered," says co-author Jean-Paul Kneib. "If this unseen army of faint, elderly galaxies is indeed out there, they could provide the missing radiation that made the Universe transparent to ultraviolet light."

As of today, we can only discover these galaxies by observing through massive clusters that act as cosmic telescopes. In coming years, the NASA/ESA/CSA James Webb Space Telescope, scheduled for launch later this decade, will specialise in high resolution observations of distant, highly redshifted objects. It will therefore be in an ideal position to solve this mystery once and for all.

More information:
The research will appear in a paper entitled Discovery of a possibly old galaxy at z=6.027, multiply imaged by the massive cluster Abell 383, to be published in the Monthly Notices of the Royal Astronomical Society.

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26 comments

Eventually, as we make better and better telescopes and arrays, scientists will discover that stars existed closer and closer to the "beginning"...eventually all the way back to...four days, or roughly 96 hours...

Looking forward to the mystery solution once and for all.... Here is a hint. The Big Bang is nonsense. Old stars in a young galaxy? The explanations keep getting more and more stretched. Keep climbing out on that limb. The article presents this fantasy theory as fact. Aren't all those first stars supposed to be short-lived first generation????

So maybe the limit of our instruments has a bearing on the nature of the discoveries we make. After all, the observation changes what is observed, according to quantum theory.

Well, yes, when you are looking at something which is supposedly that far away, you are basicly collecting individual photons, which means quantum properties become problematic.

Something else they failed to mention is that gravitational lensing is unreliable at best, since you don't actually "know" the degree of warping. For all they know, they could be looking at light which has been bent completely around the lense from THIS side.

personally, I think they should re-make around 12 upgraded versions of Hubble, an launch them as follows:

4 geostationary orbits offset by 90 degrees.4 polar orbits along an appropriate plane, offset 90degrees4 additional polar orbits along a perpendicular plane to the other orbits, offsets of 90 degrees.

Now this array of optical telescopes would allow you to potentially have perhaps 6 to 8 optical space telescopes in 3dimensions all focusing simultaneously on a single target object, and as one scope moves in orbit and loses LOS, another takes it's place.

The data from this array would allow you to combine Deep Fields to produce composite 3-d perspective images with exceptional resolution, essentially simulating an 12,800km telescope, but with no atmospheric interference.

Additionally, observation time for individual scopes could be arranged to make use of the time when they are not able to view the primary target(s).

Eventually, as we make better and better telescopes and arrays, scientists will discover that stars existed closer and closer to the "beginning"...eventually all the way back to...four days, or roughly 96 hours...

I don't think you understand what a "day" is or why the concept of a "day" is meaningless here...

Now this array of optical telescopes would allow you to potentially have perhaps 6 to 8 optical space telescopes in 3dimensions all focusing simultaneously on a single target object, and as one scope moves in orbit and loses LOS, another takes it's place.

The data from this array would allow you to combine Deep Fields to produce composite 3-d perspective images with exceptional resolution, essentially simulating an 12,800km telescope, but with no atmospheric interference.

Additionally, observation time for individual scopes could be arranged to make use of the time when they are not able to view the primary target(s).

What if we had say 100 Hubble telescopes up there? It would really make difference because the cosmos is so big we can't comprehend it, not even You Quantom (no it all) Guy.

Looking forward to the mystery solution once and for all.... Here is a hint. The Big Bang is nonsense. Old stars in a young galaxy? The explanations keep getting more and more stretched. Keep climbing out on that limb. The article presents this fantasy theory as fact. Aren't all those first stars supposed to be short-lived first generation????

In case you hadn't noticed, this is what the writer actually wrote:

...indicated that the galaxy was made up of **surprisingly old and relatively faint** stars. This told us that the galaxy was made up of stars already nearly 750 million years old pushing back the epoch of its formation to about 200 million years after the Big Bang, much further than we had expected

and that makes perfectly reasonable sense.If our Sun is 5 billion years old, then those stars must have been very much bigger with much quicker life span.

Giant galactic clusters early on in the universe? Structures evenly spaced early in history similar to today in an expanding universe? Tremendous ejections from galactic centers having star forming regions such as M82 and Centarus A? Young population of stars near center of M31, with it's periodic ring structure? Stars moving away from our own galactic center almost anywhere sampled?http://www.physor...ter.html

Isn't it time to rethink presumptions? Taken alone, a news item can be discounted. Consider the sum instead...

the centre of this image contains so much dark matter mass that its gravity bends light.

So dark matter is now a reality. Just like evolution from one ancestor to all living organisms. Repeat it often enough and magically it becomes true.

including that its stars were unexpectedly old for a galaxy this close in time to the beginning of the

I've said it before, more and more of these galaxies and stars closer to the mythical "beginning" of the big bang will be found to be just as stale and old looking as those closer to us. This falsifies the big bang as it currently stands.

other distant galaxies that have been observed, which generally shine brightly with only young stars.

Other galaxies have also been found quite close to us, having only bright young stars. So how does one differentiate between what is far and "should be young" and what is closer to home? You can't. Not until you've catalogued ALL of them. And that's going to take a lot of time. LOTS of time

more and more of these galaxies and stars closer to the mythical "beginning" of the big bang will be found to be just as stale and old looking as those closer to us. This falsifies the big bang as it currently stands.

That said, I am no cosmologist, don't have the training nor the math to truly add to the scientific debate, be it 'for' or 'against'. Nor do I have any emotional investment in BB theory being true or false. But then, my view of my place in the universe does not hinge on an irrational, 'at all costs' belief in the universe being 6,000 years old.

Believe in your god, Kev, by all means. But the bible is not a literal document - accept it, and move on.

ZephirAWT

Such observations could falsify the Big Bang model easily. In dense aether model of Universe the black holes are forming giant fluctuations and they're condensing and evaporating randomly throughout the whole Universe like density fluctuations inside of gas with fixed entropy content.

All I'm saying is that it will piss me off to no end if they start finding out that the first galaxies started forming a billion years before the big bang...

young bright stars are easier to see than older stars (Which are all smaller as big stars have short lifetimes, so non star forming and non quasar galaxies will be much harder to detect...things that we consider more common our part of the universe...) Like I always say, I'm not saying that the basics of the theory is wrong, but I am saying that they severely discount the possibility of observational bias due to natural limitations.

The evidence for the Big Bang theory is profound. Both observational and theoretical. To say that because there are unexplained observations that the entire theory needs to be tossed is to simply misunderstand science. There are ALWAYS unexplained observations. While occasionally this does mean that the theory needs serious rework, it usually means that the correct explanation hasn't been discovered.

400 million years, and 750 million years are really long stretches of time. What this observation is really telling us is that our theories about star generation in the absence of metals need revising, or that we need to rethink the possibility of many generations of first order stars occurring in smaller spaces enabling metal enrichment to occur, which would then permit the type of small red stars we see to form

The very first stars formed had basically no metals, because there wasn't any created in the big bang (except for small amounts of lithium). Gas without metals loses heat slowly, so it takes awhile for them to contract. However, in a very high gravity gradient, which will be occasionally present just by chance, they will form massive stars (50-200 stellar masses) which then explode in ~1 myr efficiently creating a lot of metals. Given the same high gravity gradient, the next generation will have more metals, so that its quite possible in ~50-75myr to have stars with a low but reasonable metal content, allowing the formation of small red stars (which require some metals to form). In this scenario, while most galaxies would have mostly new stars which is what we see, we would expect to find a few that have a lot more "older" stars.

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